Yesterday I made a stupid mistake. I wanted to get rid of a received dust transaction of 547 sat and tried to send it to a another address with a very low fee of only 336 sat.

Here is a guide showing how to dump the dust if you use Electrum: https://gist.github.com/ncstdc/90fe6209a0b3ae815a6eaa2aef53524c

The transaction sends the 547 sats to a miner. The benefit of the OP_RETURN is that it doesn't create a UTXO that will never be spent. It works with hardware wallets, too.